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Asthma in adults - Introduction

Description

An in-depth report on how asthma is diagnosed, treated, and managed in adults.

Introduction:

The word asthma originates from an ancient Greek word meaning panting. Essentially, asthma is an inability to breathe properly. When any person inhales, the air travels through the following structures:

Air passes into the lungs and flows through progressively smaller airways called bronchioles. The lungs contain millions of these airways.
All bronchioles lead to alveoli, which are microscopic sacs where oxygen and carbon dioxide are exchanged.

The major features of the lungs include the bronchi, the bronchioles, and the alveoli. The alveoli are the microscopic blood vessel-lined sacks in which oxygen and carbon dioxide gas are exchanged.

Asthma is a chronic condition in which these airways undergo changes when stimulated by allergens or other environmental triggers. Such changes appear to be two specific responses:

The hyperreactive response (also called hyperresponsiveness)
The inflammatory response

These actions in the airway cause coughing, wheezing, and shortness of breath (dyspnea), the classic symptoms of asthma.

Hyperreactive Response

In the hyperreactive response, smooth muscles in the airways of the lungs constrict and narrow excessively in response to inhaled allergens or other irritants. Everyone's airways respond by constricting when exposed to allergens or irritants, but a special hyperreactive response occurs in people with asthma:

When people without asthma breathe in and out deeply, the airways relax and open to rid the lungs of the irritant.
When people with asthma try to take those same deep breaths, their airways do not relax and narrow, causing patients to pant for breath. Smooth muscles in the airways of people with asthma may have a defect, perhaps a deficiency in a critical chemical that prevents the muscles from relaxing.

Inflammatory Response

The hyperreactive stage is followed by the inflammatory response, which generally contributes to asthma in the following way:

In response to allergens or other environmental triggers, the immune system delivers white blood cells and other immune factors to the airways.
These so-called inflammatory factors cause the airways to swell, to fill with fluid, and to produce a thick sticky mucus.
This combination results in wheezing, breathlessness, an inability to exhale properly, and a phlegm-producing cough.

Click the icon to see an image of a normal bronchiole versus an asthmatic bronchiole.

Inflammation appears to be present in the lungs of all patients with asthma, even those with mild cases, and plays a key role in all forms of the disease.

Resources

www.lungusa.org -- The American Lung Association
www.acaai.org -- American College of Allergy, Asthma & Immunology
www.aaaai.org -- American Academy of Allergy, Asthma & Immunology
www.nhlbi.nih.gov -- National Heart, Lung, and Blood Institute
www.nationaljewish.org/disease-info/diseases/asthma/index.aspx -- National Jewish Medical and Research Center
www.aafa.org -- Asthma and Allergy Foundation of America
www.aarc.org -- American Association for Respiratory Care

References

American Lung Association. Trends in asthma morbidity and mortality. American Lung Association Epidemiology & Statistics Unit Research and Program Services. November 2007.

Ernst P, Baltzan M, Deschenes J, Suissa S. Low-dose inhaled and nasal corticosteroid use and the risk of cataracts. Eur Respir J. 2006 Jun;27(6):1168-74. Epub 2006 Feb 15.

Glassroth J. The role of long-acting ß-agonists in the management of asthma: Analysis, meta-analysis, and more analysis. Ann Intern Med. 2006 Jun 20; 144:936-7.

Kiljander TO, Harding SM, Field SK, Stein MR, Nelson HS, Ekelund J, et al. Effects of esomeprazole 40 mg twice daily on asthma: a randomized placebo-controlled trial. Am J Respir Crit Care Med. 2006 May 15;173(10):1091-7.

Kearney DM, Lockey RF. Osteoporosis and asthma. Ann Allergy Asthma Immunol. 2006 Jun;96(6):769-74.

Kukkonen K, Savilahti E, Haahtela T, Juntunen-Backman K, Korpela R, Poussa T, et al. Probiotics and prebiotic galacto-oligosaccharides in the prevention of allergic diseases: a randomized, double-blind, placebo-controlled trial. J Allergy Clin Immunol. 2007 Jan;119(1):192-8. Epub 2006 Oct 23.

National Asthma Education and Prevention Program Expert Panel Report: Guidelines for the Diagnosis and Management of Asthma Update on Selected Topics -- 2002. Rockville, MD. National Heart, Lung, and Blood Institute, US Dept of Health and Human Services; 2003. NIH publications 02-5074.

National Asthma Education and Prevention Program Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma. Rockville, MD. National Heart, Lung, and Blood Institute, US Dept of Health and Human Services; 2007. NIH publications 08-4051.

Rowe BH, Spooner CH, Ducharme FM, Bretzlaff JA, Bota GW. Corticosteroids for preventing relapse following acute exacerbations of asthma. Cochrane Database Syst Rev. 2007 Jul 18;(3):CD000195.

Salpeter SR, Buckley NS, Ormiston TM, Salpeter EE. Meta-analysis: effect of long-acting beta-agonists on severe asthma exacerbations and asthma-related deaths. Ann Intern Med. 2006 Jun 20;144(12):904-12.

Slavin RG, Haselkorn T, Lee JH, Zheng B, Deniz Y, Wenzel SE; TENOR Study Group. Asthma in older adults: observations from the epidemiology and natural history of asthma: outcomes and treatment regimens (TENOR) study. Ann Allergy Asthma Immunol. 2006 Mar;96(3):406-14.

Reviewed last on: 6/26/2008
A.D.A.M. Editorial Team: David Zieve, MD, MHA, Greg Juhn, MTPW, David R. Eltz. Previously reviewed by Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. (4/24/2008)

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